They would not do it. 1, a revolt would happen for their products, 2, it would open the door for a rival or newcomer. Hp and others I am sure would love to sell a google OS PC, they could sell it cheaper and with higher profit margin, win/win. Only loser would be MS. This is why I do not think they would do it. Altering the desktop gaming would ruin their goose.

That sounds good in theory but it just can't be that simple.

For one, a Google-powered machine today has almost NO appeal to a hardcore gamer.

Right now Google-powered gaming is essentially Angry Birds. Browser and flash-based games. One has to wonder of the top-flight publishers will find a way to monetize blockbuster games on a Google platform - my guess is that it just won't be lucrative.